English how-to · updated 2026
A daily school, exam, and bill search — marks, discounts, and GST maths. This page has 50 important questions and answers. Original explainer for daily search — not a government login or live tracker.
A percentage is “per hundred.” To find X% of Y, compute (X ÷ 100) × Y. To find what percent A is of B, compute (A ÷ B) × 100. To find the new price after a 20% off sale, take 80% of the old price — or subtract 20% of it.
Exam marks: (marks scored ÷ total marks) × 100. A 15/20 test is 75%. GST on a bill: if the tax is 18% inclusive, the tax portion is not the same as 18% added on top — inclusive and exclusive GST use different rearrangements.
Percent change is ((new − old) ÷ old) × 100. A rise from 80 to 100 is +25%, not +20. People mix this up every day on salary and inflation headlines.
50 important questions. Quick 10 is a random set; Full set plays every question.
Original explainers for English readers — not copied match reports or official papers. Tap a question to see the answer.
Answer: (X ÷ 100) × Y
20% of 250 is 50.
Answer: 90%
(36 ÷ 40) × 100 = 90.
Answer: ₹640
20% of 800 is 160; 800 − 160 = 640.
Answer: 25%
(20 ÷ 80) × 100 = 25.
Answer: 0.90
Sale = 90% of original.
Answer: 60
Half of 40 is 20; 40 + 20 = 60.
Answer: 75%
3 ÷ 4 = 0.75.
Answer: the same as a percentage-point change
Rates from 2% to 3% rose 1 point, which is a 50% rise.
Answer: 5
1% means ÷ 100.
Answer: 10
0.05 × 200 = 10.
Answer: 12
0.15 × 80 = 12.
Answer: 90
A quarter of 360 is 90.
Answer: 10
12.5% is one-eighth.
Answer: 72%
(18 ÷ 25) × 100 = 72.
Answer: 75%
45 ÷ 60 = 0.75.
Answer: 275
10% of 250 is 25.
Answer: 225
250 − 25 = 225.
Answer: 20%
(10 ÷ 50) × 100 = 20.
Answer: 300
90 ÷ 0.30 = 300.
Answer: 160
64 ÷ 0.40 = 160.
Answer: ₹210
5% of 200 is 10.
Answer: ₹180
0.18 × 1000 = 180.
Answer: 18% of the shelf price in the exclusive sense
Inclusive tax = price − price/1.18.
Answer: 100% increase
New = 200% of old; the rise is 100%.
Answer: 50% decrease
You still have half.
Answer: 60%
3 / 5 = 0.60.
Answer: 20%
Multiply by 100.
Answer: 250%
2.5 × 100 = 250.
Answer: a flat 20% off
0.9 × 0.9 = 0.81, so 19% off.
Answer: 600
20% of 500 is 100.
Answer: 360
10% of 400 is 40.
Answer: 20%
7 ÷ 35 = 0.20.
Answer: 75%
9 ÷ 12 = 0.75.
Answer: 20% of the total parts
1 of 5 parts.
Answer: 3 points
The relative rise is 37.5%, which is a different sentence.
Answer: 1.25’s opposite as “minus 25% of the new” blindly
New ÷ 1.25 = old.
Answer: 200
80 ÷ 0.40 = 200.
Answer: 74%
0.7×80 + 0.3×60 = 56+18.
Answer: 80
Interest and amount are different words.
Answer: 25% of the circle
90/360 = 1/4.
Answer: 10% of the circle
36/360 = 0.10.
Answer: (scored ÷ total) × 100 first
Then round as the board asks.
Answer: 50% off each item in every shop’s small print
Read whether the second is free.
Answer: 1 million extra
0.02 × 50m = 1m.
Answer: 15%
60/400 = 0.15.
Answer: ((24−20)÷20)×100
That is +20%.
Answer: still needs you to know of-what
Percent of the wrong base is a common bill error.
Answer: file your GST return
Use the official portal for tax filing.
Answer: new equals old
The base is unchanged.
Answer: the new value is smaller than the old
Salary cuts and price drops use the same maths.
Pick the next article in this topic — that is how a magazine issue is meant to be used.
