1.5 x 100 = 150
1.5 times 100 is 150. One and a half hundreds is one hundred plus fifty. The same step turns the decimal 1.5 into 150 percent, which is why this one gets looked up so often.
1.5 × 100 = 150
The working
Split the number at the decimal point and handle each half separately:
- 1 x 100 = 100
- 0.5 x 100 = 50
- 100 + 50 = 150
Or move the decimal point two places right in one go: 1.5 becomes 150. The split version is worth knowing because it keeps working when the numbers stop being round.
1.5 as a percentage
Multiplying a decimal by 100 converts it to a percentage, so 1.5 = 150%. Anything above 1 converts to more than 100%, which is the point of the conversion when you are describing growth or a multiplier rather than a share of something.
Where 150 shows up
The everyday version of this sum is unit pricing. One hundred items at 1.50 each comes to 150. That is the same arithmetic with a currency symbol attached, and it is the reason the pair appears so often on invoices and order forms.
The hours trap
1.5 hours is 90 minutes, not 150. Time runs in sixties, so a decimal hour converts with 60 rather than 100: 1.5 x 60 = 90. Anyone reading 1.5 off a timesheet and reaching for 100 will overstate it by an hour.
Separately, 1.5% of 100 is 1.5, not 150. The percent sign has already done the dividing.
Nearby decimals
2.5 x 100 = 250, 0.5 x 100 = 50, and the whole-number cousin 15 x 1000 = 15000.