We've already seen how to multiply a one digit number with another one digit number. So what do we do when it's a two digit number multiplied with another $2$2 digit number?
When we multiply we are always talking about groups. $13\times24$13×24 is actually saying $13$13 groups of $24$24 or $24$24groups of $13$13. We could add up all these groups, but that is a lot of addition to do in our head! There is actually an easier way. Watch this video to see how.
Multiply two-digit whole numbers by two-digit whole numbers, using estimation, student-generated algorithms, and standard algorithms