Find 22.5% of $160
- 22.5% = 0.225.
- 0.225 × 160 = $36.
- 20% is $32, so $36 is a reasonable result.
Find the part
Use a percent to scale a known whole.
Part = percent as a decimal × whole
Finding a percent of an amount is multiplication. If a percent is p, the multiplier is p/100. Therefore part = (p/100) × whole. Label the part and whole before substituting. The answer carries the unit of the whole: dollars, metres, people or another quantity.
Scale the whole by a percent.
Predict first. Change one value, then explain what stays the same and what changes. All bars use the same scale within a model.
Connect the formula to a tape diagram
A tape labelled 100% represents the whole. A 30% segment is 0.30 of its length, so 30% of 90 is 0.30 × 90 = 27. The formula records the same scaling shown by the picture; it is not a separate trick.
Check the size of the part
For a positive whole, a percentage between 0% and 100% gives an amount between zero and the whole. A percent over 100% gives more than the whole. Keep intermediate precision, and round a money answer to cents at the stated payment stage. Counts of indivisible objects need a context-appropriate interpretation.
Worked examples
Find 0.75% of 4800 m
- 0.75% = 0.0075.
- 0.0075 × 4800 = 36 m.
- 1% is 48 m; three quarters of that is 36 m.
Guided Practice
A 240 m route is shortened by 12.5%. How many metres are removed?
A first hint
The question asks for the removed part, not the route left.
Compare your reasoning
0.125 × 240 = 30 m removed. The new route would be 210 m.
Practice
Fresh questions · useful feedback
Build fluency, one decision at a time.
Work through eight questions. Two independent correct answers introduce a harder version; supported answers bring the next question back to the foundation. You can use hints at any time.
0 of 8 questions completed
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Connections
A 160% portion of a 45 g serving is prepared. Find its mass and explain why a part can be larger than the reference whole.
Use it in Extreme Couponing
Record the whole, the percent multiplier and the result with units. For each coupon, use the eligible amount at that step. State whether a resale percentage means percent of cost or markup on cost.