Question Video: Subtracting Three-Digit Numbers Using Column Subtraction Mathematics • 2nd Grade

Find the result of the following: 865 − 384


Video Transcript

Find the result of the following: 865 subtract 384 equals what.

We don’t really need to think about which method we want to use to find the answer to the subtraction. It’s been set out as a column subtraction already for us. So we’ll use the standard written method. First, we subtract the ones. 865 has five ones, and 384 has four ones. And the difference between five ones and four ones is one one. Onto the tens. 865 contains six 10s, and 384 contains eight 10s. At the moment, we can’t subtract eight 10s. We don’t have enough 10s in our tens column. We’re going to need to regroup our starting number. We’ll start by taking one of our 100s. Instead of eight 100s, we now have seven 100s. And we need to regroup this into 10 10s. So instead of six 10s in our tens column, we can put a little one to show we have 16 10s.

We haven’t changed the value of our starting number at all. Seven 100s, 16 10s, and five ones are exactly the same as 865. But by regrouping the number like this, we do have enough 10s to subtract eight 10s. So we have 16 10s; we need to take away eight 10s. We know that eight and eight makes 16, so we’re going to be left with eight 10s. Finally, the hundreds, 865 has eight 100s, and 384 has three 100s. But don’t forget, we’re not subtracting three from eight 100s because we’ve exchanged one of our 100s. We’ve only got seven 100s left in the hundreds place. So seven 100s subtract three 100s leaves us with four 100s. 865 subtract 384 equals 481.

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