How to Calculate Percentages: Formula, Worked Examples & Practice
Published: 14.05.2026·Updated: 15.10.2026
Nadia Rahmawati
Math Curriculum Team, Algonova
How to calculate a percentage uses the formula Percentage = (Part ÷ Total) × 100%. For example, 45 correct out of 60 questions is (45 ÷ 60) × 100% = 75%. The same formula covers discounts, taxes and price rises. It is first taught in Year 5.
The Three Forms
Find the percentage: (Part ÷ Total) × 100%
Find the part: (Percentage ÷ 100) × Total
Find the total: (Part ÷ Percentage) × 100
Worked Examples
45 of 60: 75%.
25% discount on Rp200,000: Rp50,000, final price Rp150,000.
Rp60,000 is 30% of pocket money: total Rp200,000.
15% of 80 = 0.15 × 80 = 12, not 1,200.
Price from Rp40,000 to Rp48,000: up 20%.
Discounts
Final price = original price × (100 − discount%) ÷ 100. A Rp350,000 pair of shoes at 40% off costs Rp210,000. Stacked discounts of 50% and 20% give Rp160,000 from Rp400,000, which equals 60% off, not 70%. With 11% VAT, Rp100,000 less 20% is Rp80,000, then Rp88,800.
Summary
Convert the percent to a decimal first. Algonova has helped more than 1,000,000 students in 97 countries, with a free 45-minute maths diagnostic.
Calculating percentages is first studied in Year 5 of SD (primary school), then taken further in Year 6 of SD and Year 7 of SMP (junior secondary school). At SD students meet the percentage as a fraction per hundred, while at SMP percentages are used for discount, interest and more complicated comparison problems. This is among the material most used throughout life, from shopping to personal finances.
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Frequently Asked Questions
Does Algonova teach mathematics for primary, junior high, and senior high kids?
Yes, Algonova Indonesia offers a complete math program for kids aged 6 to 17, covering all school levels from primary, junior high, to senior high. Each level has a dedicated curriculum aligned with the child's cognitive stage and the Indonesian school curriculum (Kurikulum Merdeka).
For primary school (6-12): basic operations, fractions, simple geometry, and introduction to algebra. For junior and senior high (13-17): algebra, quadratic equations, basic trigonometry, advanced geometry, basic calculus, statistics, UTBK SNBT preparation, and advanced topics.
All classes are online live with certified teachers in small groups of up to 10 students per class. Our method is built on visual conceptual understanding, not formula memorisation. Try a free trial class for a child's level diagnostic and recommended learning path.
Is there a free trial class for kids math tutoring?
Yes. For mathematics Algonova Indonesia offers a free 45 minute diagnostic session with no commitment. The format is called Metode Diagnostik Algonova. No credit card is needed and there is no auto subscription afterwards. Note that these 45 minutes are a diagnostic session, not a regular class. A regular math class runs 90 minutes, while the coding and design tracks have their own introductory format, a free 60 minute master class.
During the diagnostic a certified teacher maps the child's level: which topics are already solid and where the gaps sit. The child also tries the online learning platform and works through first problems matched to their school level.
After the session parents receive a personal learning plan based on the diagnostic result, plus a transparent explanation of program, schedule, and pricing from Rp 102,000 per lesson. To book, fill in the form on the website.
How many students are in one Algonova math class?
Algonova Indonesia math classes come in three formats: 1-on-1 private, a mini-group of 2–4 kids, and a group of up to 10 students with similar ability and school grade levels. This small group format is deliberately chosen because it provides the optimal balance between social interaction with peers and personal teacher attention.
In a mini-group, every child averages about 10 minutes of direct teacher interaction in a single session. Compare with traditional offline bimbel typically of 20-40 students per class — direct interaction there is only 1-2 minutes per child, or none at all.
For families wanting full attention, one-on-one private class format is also available with one student per teacher. This format is more intensive and suits competition preparation, catching up from severe gaps, or specific topic depth.
How much does kids math tutoring at Algonova Indonesia cost?
Kids math tutoring at Algonova Indonesia starts from Rp 102,000 per lesson. The price includes a live session with a certified teacher, digital learning materials, online platform access, and an official certificate upon completing each program level.
The transparent 'starting from' rate is the same across all school levels — the final quote depends only on class format (private, mini-group, or group) and how many sessions per week you choose. Groups are the most affordable option; private classes are more intensive and suit competition prep or closing larger gaps.
Full pricing details are shared transparently after the free trial class. No surprise fees — every cost component is explained before formal enrolment. To receive the latest pricing details, fill in the booking form on the website.
Is math tutoring fully available online?
Yes, all Algonova Indonesia math programs are fully available online with live sessions taught by certified teachers — not recorded videos. Kids learn in real time in small groups of up to 10 students, with two-way interaction, live Q&A, and problems worked on alongside the teacher throughout the class.
To join online class, a child only needs a computer or laptop with a camera, a stable internet connection, and a headset. The Algonova platform runs directly in the browser so no special software installation is required. Kids can write problems in a regular notebook or on a tablet with stylus.
Because every class is fully online, families can join from anywhere in Indonesia and easily fit lessons around school and other activities.
What makes Algonova math tutoring effective for Indonesian kids?
Three main factors make Algonova math tutoring effective for Indonesian kids. First, the curriculum aligns with Kurikulum Merdeka used in national schools, so what is learned at Algonova directly helps with school lessons and exams.
Second, the methodology is built on visual conceptual understanding (not formula memorisation). Kids learn to break big problems into small systematic steps — a thinking pattern transferable to other subjects like science and IT.
Third, small groups of up to 10 students per class let teachers adjust pace to each child's ability. Slower kids get personal help, while faster kids don't get bored waiting. The result: most Algonova students see math grade improvements at school within the first 2-3 months.
What if my child is behind from earlier math grades?
Algonova Indonesia is specifically designed to help kids behind catch up in a way that doesn't make them feel defeated or ashamed. Every new student starts with a free diagnostic during the trial class to identify exactly where the gap occurred.
Based on the diagnostic, the teacher builds a personal learning path that closes the gap from the most basic foundation. For example, a junior high student weak in algebra might actually be behind in primary school fraction operations. We go back to the foundation, then progress gradually without comparison with other peers.
Many Algonova students who initially started 1-2 grade levels behind successfully caught up and even surpassed classmates within 3-6 months with weekly classes and consistent homework. It's never too late to start. Try a free trial class for diagnosis without commitment.
What is a percentage?
Percent (%) is a way of expressing a number as a part out of 100. For example, 75% means 75 out of every 100, or three-quarters of the whole. The % symbol is used to express proportions, discounts, exam scores, and many other comparisons in everyday life.
What is the formula for calculating a percentage?
The basic formula for calculating a percentage is: Percentage = (Part ÷ Total) × 100%. To find the part: Part = (Percentage ÷ 100) × Total. To find the total: Total = (Part ÷ Percentage) × 100.
What is the most common mistake when calculating percentages?
The most common mistake is forgetting to divide by 100 before multiplying. For example, 25% of 80 is not 25 × 80 = 2,000, but (25 ÷ 100) × 80 = 20. Always convert the percentage to decimal form (divide by 100) first before multiplying by the total value.
Where are percentages used in everyday life?
Percentages are used everywhere: calculating shopping discounts, exam scores, taxes, savings interest, nutritional content of food, even weather data and surveys. Understanding how to calculate percentages helps you make smarter financial decisions from an early age.
At what year are percentages taught in Indonesia?
The concept of percentages is first introduced in Year 5 of primary school in the Indonesian curriculum, and developed further in Year 6 of primary school and Year 7 of middle school. In middle school, pupils start applying percentages to more complex problems involving interest, discounts, and ratios.
How do you calculate a percentage increase or decrease?
The formula for percentage increase/decrease is: ((New Value − Old Value) ÷ Old Value) × 100%. A positive result means an increase; a negative result means a decrease. Example: a price rises from Rp100,000 to Rp120,000 → ((120,000 − 100,000) ÷ 100,000) × 100% = 20% increase.
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