Move the decimal point one place to the right, or add a zero.

Example:

The 2-digit number chosen to multiply by 1 2/3 is 78.

Divide by 2: 78/2 = 39

Divide by 3: 39/3 = 13. (39 is divisible by 3 because the sum of its digits is
divisible by 3.)

Add a zero: 130.

So 78 × 1 2/3 = 130.

See the pattern?

If the 3-digit number chosen to multiply by 1 2/3 is 315:

Divide by 3: 315 / 3 = 105. (315 is divisible by 3 because the sum of its digits
is divisible by 3.)

Divide by 2: 105/2 = 52.5.

Move the decimal point one place to the right: 525.

So 315 × 1 2/3 = 525.

Test the number to see if it is divisible by 3 (if the sum of the digits is divisible
by 3, so is the number). If not, divide by 2 first. This should make the division
easier.