TablesHardly anyone needs to chant the table of 27. What is useful, for mental maths and for exams, is being able to produce any line of these tables in a few seconds. This page gives the chart for checking and printing, and the two methods that produce every line.
Method 1: from the round number below
For 21, 22, 23 and 24, start from twenty times and add. 23 × 7 is 140 plus 21, which is 161. For 26, start from twenty-five times: 26 × 4 is 100 plus 4.
Method 2: from the round number above
For 27, 28 and 29, start from thirty times and take away. 29 × 6 is 180 minus 6, which is 174. 28 × 7 is 210 minus 14, which is 196. Taking away a small amount from a round number is often easier than adding two awkward parts.
The special ones
- 25: four 25s make 100. So 25 × 8 is 200 and 25 × 12 is 300. The answers end 25, 50, 75, 00.
- 30: the table of 3 with a zero after it.
- 22, 24, 26, 28: double the tables of 11, 12, 13 and 14.
- 21 and 27: three times the tables of 7 and 9.
- 23 and 29 are prime.
How to read and print the chart
Each card is one table up to × 10, and each number has its own page with the table up to × 20. Press Print to get only the chart on paper.
Where these tables help
Hours and days (24, 28, 29, 30), quarters of a hundred (25), the alphabet (26) and weeks (21 and 28 are 3 and 4 weeks) all sit in this group. In competitive exams, knowing squares to 30 and being quick with these tables saves a good deal of rough work in percentage and time-and-work questions.