Any number is said to be divisible by 7, when you subtract “double of ones digit” from the number excluding the ones digit and the result is divisible by 7.

For example: Is 315 divisible by 7?

Step 1: Last digit of 315 is 5, so figure = 31 – (2 x 5) = 31 – 10 = 21

Step 2: Check if figure, 21 is divisible by 7.

Here, 21 ÷ 7 = 3, i.e. 21 is perfectly divisible by 7.

Hence, number 315 is divisible by 7.

Note: If the figure is a big number, then this technique can be continued till you get a smaller 1 or 2 digit figures.

For example: Is 222224 divisible by 7?

Step 1: Figure 1: 22222 – (2 x 4) = 22216

Step 2: Figure 2: 2221 – (2 x 6) = 2209

Step 3: Figure 3: 220 – (2 x 9) = 202

Step 4: Figure 4: 202 – (2 x 2) = 16

As 16 is not divisible by 7, so our number 222224 is also not divisible by 7.

Practice Questions:

Check whether below numbers are divisible by 7?

a. 4566             b. 1246            c. 1120        d. 5642              e. 22124

f.  24                 g. 3636             h. 978         i. 2840                j. 5556