1.2.3 Multiplying by 25 Trick

The trick to multiplying by 25 is to think of it as 100/4. So the strategy is to take whatever you are multiplying with, divide it by 4, then move the decimal over to the right two places.

Example: 84 × 25

Step	Calculation
Divide by 4	84 ÷ 4 = 21
Multiply by 100	21 × 100 = 2100

Example: 166 × 25

Step	Calculation
Divide by 4	166 ÷ 4 = 41.5
Multiply by 100	41.5 × 100 = 4150

Dividing by 25

In a similar manner, you can use the same principle to divide numbers by 25 easily. The difference is you multiply by 4 and then move the decimal over to the left two places.

Example: 415 ÷ 25

Step	Calculation
Multiply by 4	415 × 4 = 1660
Divide by 100	1660 ÷ 100 = 16.6

Problem Set 1.2.3

240 × 25

25 × 432

2.6 × 2.5

148 × 25

25 × 33

64 ÷ 25

25 × 147

418 × 25

616 ÷ 25

2.5 × 40.4

1.1 ÷ 2.5

3232 × 25

97531 ÷ 246 *

209 × 25

(18 + 16)(9 + 16)

334455 ÷ 251 *

404 ÷ 25

303 × 25

2006 ÷ 25

25 × 307

25 × 2003

15 × 25 × 11

11 × 24 × 25

11 × 18 × 25

248 × 250 × 252 *

Percentage Problems

21.4 is what % of 25?

32 is 2½% of:

Comparison Problems

Which is smaller: 6/25 or 0.25?

Which is larger: 7/25 or 0.25?

* Questions marked with an asterisk accept answers within 5% tolerance.