How do you multiply 2 digit by 2 digit?

Answer 1

There are many different methods which are taught in schools and it is best that you stick with the "approved" method in your early days. Many teachers may disapprove if you use different methods.

One method is called the grid method [and it relies on the associative property of multiplication over addition]. It is very similar to the chunking method. This browser is probably the worst thing in the world to try and show the method but I'll try. Remember that all the full stops are merely space fillers.

Suppose you want to multiply 47 by 86

then 47 = 40 + 7 and 86 = 80 + 6

You make a 2x2 grid with 40 and 7 across the top and 80 and 6 down the side. The number in each cell is the product of the corresponding column and row heading. Thus:

___x____40___|___7_|

------------------------------------

__80___3200_|_560_|

___6____240_| __42_|

Finally, add together all the number in the 4-cells of the grid.

3200 + 560 + 240 + 42 = 4042.

So 47 * 86 = 4042.

Answer 2

To multiply two-digit numbers by two-digit numbers, use the long multiplication method. Write down the numbers vertically, multiply the ones' digits, carry over if needed, multiply the tens' digits, and finally add the partial products together to get the final result.