When a number is multiplied by four, double it and then double it again. Teach your students the pattern of the three multiplication table as if it were a phone number, (369) 258-1470. For example, numbers that end with a nine that are then multiplied by three are going to then become a number that ends with a seven. If students can remember this order they will at least know what the last digit of any multiplication of three is.
The last digits in both groups are the same: 3, 6, 9, 2, 5, 8, 1, 4, 7, 0. The last digit of these multiples always repeat, which means that students can remember these digits to help them with the three multiplication tables. Three doesn’t have any rules that make its multiplication table easy to memorize, but there is a pattern for every ten multiples of three: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30
