# Multiplication Table Question

1. Oct 28, 2014

### Thecla

Why do many multiplication tables for grade school students go up to 12x12, when a table up to 9x9 is sufficient for any multiplication problem?

2. Oct 28, 2014

### symbolipoint

Quickest guess is that DOZEN is a common or frequently used denomination or set of increments.

3. Oct 28, 2014

### HallsofIvy

Because knowing "11 times" and "12 times" by heart is a little faster than doing it as 10+ 1 and 10+ 2. And, as symbolipoint said, dozens are used often enough to make that useful. (11 just gets in the way!)

4. Oct 28, 2014

### symbolipoint

Twelves is just a little bit beyond the basic multiplication facts necessary for both mental and manually written competence with performing multiplication computations. Nothing really stops a person from memorizing up to 13 or up to 16 or 17, or whatever one wants to know or memorize. Beyond twelves, knowing a few facts can be convenient or can come through experience: 13 squared is 169; 14 squared is 196; 15 squared is 225; 52 is the typical amount of cards in a set of playing-cards, and from this one may know 13*4=52.

5. Oct 28, 2014

### Thecla

Thanks for the help. I forgot about the dozen

6. Oct 30, 2014

### bhillyard

In the UK it goes back to before 1972 when our currency had 12 pennies to 1 shilling.