How to judge the single digits of a multi-digit number?

In fact, to calculate the single digits of the product of two numbers, just multiply the single digits of these two numbers to get the single digits of the number you want. For example, 2 32 = (216) 2 = (210 * 2 6) 2 = (1024 * 64) 2,1024 and 64 are all single digits 6, so