15 times table

The 15 times table up to 15 × 12

The 15 times table is 15, 30, 45, 60, 75, 90, 105, 120, 135, 150, 165, 180. It goes past the 12 × 12 multiplication chart, so most schools do not require it: the Common Core stops at one-digit facts and England at 12 × 12. It turns up every day on the clock, in quarter hours, and in 4th and 5th grade work with minutes, money and long multiplication. The chart above has every fact, and "Hide answers" turns it into a quick self-check.

Multiplication by 15: ten groups and half again

Multiplication by 15 has a neat shortcut: multiply by 10, then add half of that answer. 15 × 4 = 40 + 20 = 60; 15 × 8 = 80 + 40 = 120; 15 × 12 = 120 + 60 = 180. Half of an odd tens number is easy too: half of 90 is 45, so 15 × 9 = 90 + 45 = 135.

Quarter hours on the clock

15 minutes is a quarter of an hour, so the 15 times table walks around the clock: 15, 30, 45, 60. "How many minutes are 3 quarter hours?" is 15 × 3 = 45. The answers end in 5 and 0 by turns: an odd number times 15 ends in 5, an even number times 15 ends in 0.

15 times table games and worksheet

The trainer asks the 15 times table out of order with a keypad. The facts children mix up most are 15 × 7 = 105, 15 × 9 = 135 and 15 × 11 = 165 (115, 145 and 155 are the usual slips), so the game brings a missed fact back two or three questions later until it is right three times in a row. When the round feels easy, take the speed test and then the test for the diploma. The 15 times table worksheet prints 30 problems with the answer key on page 2, and the third sheet practices the trick.

A tip for parents

Count in 15s along a real clock face with your child: quarter past, half past, quarter to, o'clock. Then ask "how many minutes in 5 quarter hours?" - 75. Ask the facts the other way round too: 7 × 15 is the same as 15 × 7.