Video: KS2-M16 • Paper 1 • Question 11

71 × 8 = _.


Video Transcript

71 multiplied by eight equals what?

To make this calculation more manageable, we can partition 71 into 70 and one. So if we can find the answers to 70 times eight and then one times eight and then add the two together, it will give us the answer to 71 times eight.

What is 70 multiplied by eight? Well, seven eights are 56. 70 is 10 times greater than seven. So our answer will be 10 times greater than 56. 70 times eight equals 560. And one times eight equals eight. And if we write it over here, it’ll help us add the two answers together. 560 plus eight equals 568.

First, we partitioned our two-digit number into its tens and ones. So 71 became 70 and one. Then we multiplied each of those parts by eight. First, we multiplied the tens, and we used a number fact we already knew to help us. Then we multiplied the ones. And then finally, we combined both parts back together again. We added the two answers together. 71 multiplied by eight equals 568.

Just as an added extra, can you see anything interesting about our answer? Our question asked us to multiply 71 by eight. Seven eights are 56, and one eight is eight. Both facts are visible in our answer. This isn’t a maths trick that works every single time. This only works because there is a one in the ones column. But it’s still an interesting pattern to notice.

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