Explain that with multiplication you can put the numbers one under the other and multiply them working from right to left. This is called standard algorithm multiplication. Show that above each column there is a box for regrouping. In these boxes you can write down the numbers that are carried over and add them to the other outcomes later. Show the example of how you set up the problem 91 x 3. You start multiplying using the standard algorithm. First you multiply the numbers in the ones column together. 3 x 1 = 3. After that you multiply with the number in the tens column. The problem then is 3 x 90 = 270. Now you add up the answers in the intermediate step. 270 + 3 = 273. You write this answer under the line. Emphasize that you don't write down the intermediate step, but fill in the numbers directly under the line. Now solve the two problems together with the students. You may let the students use scrap paper to write down the intermediate steps. Next the students solve the following three problems on their own.
Check whether the students can multiply using the standard algorithm with a number to 100, by asking the following question:
- What steps do you take to solve the problem 32 × 4 using the standard algorithm?