60 Is 15 of What Number? How to Find the Whole
60 is 15% of 400. In other words, if 15 percent of some unknown number equals 60, that number is 400. Here’s how to get there.
Set Up the Equation
The phrase “60 is 15% of what number” translates into an equation. Let x stand for the unknown whole. “Is” becomes the equals sign, “15%” becomes a decimal, and “of” means multiplication:
60 = 0.15 × x
Converting a percent to a decimal is the key move. Percent means “per hundred,” so 15% equals 15 ÷ 100, or 0.15. Khan Academy explains this conversion as moving the decimal point two places to the left. For example, 25% becomes 0.25, and 7% becomes 0.07.
Solve and Verify
Isolate x by dividing both sides by 0.15:
x = 60 ÷ 0.15
Since 0.15 goes into 60 exactly 400 times, x = 400. Verify it: 400 × 0.15 = 60, which matches the original statement. This is the same process Khan Academy uses for finding the whole when a part and its percent are known.
A quick sanity check: if you guessed 300, then 300 × 0.15 = 45, not 60. So 300 fails and 400 holds.
Dividing by a decimal can feel backwards. The equation 60 = 0.15 × x says that 60 is a fraction of x, so you undo the multiplication with division. And because 15% is small, the whole must be much larger than the part — which is why the answer, 400, is far bigger than 60.
Key Takeaways
- The sentence “60 is 15% of what number” becomes the equation 60 = 0.15 × x.
- Convert the percent first: 15% = 0.15.
- Divide the part by the decimal: 60 ÷ 0.15 = 400.
- Always verify by multiplying back — 400 × 0.15 = 60 confirms the answer.
