Adding Six-digit NumbersDate: 12/23/96 at 09:49:37 From: Sarah Hobbs Subject: Adding I've done everything I can to try and figure out the sum of 100,234 and 678,123. Date: 12/24/96 at 01:27:54 From: Doctor Mike Subject: Re: Adding Hi Sarah, Sometimes you can add numbers easily by just adding the numbers in the "ones" place, then the numbers in the "tens" place, then the numbers in the "hundreds" place, and so on. In this problem you are in luck! Let's take a look. The first number ends with 4 ones, and the second number ends with 3 ones. That makes 7 ones. We start writing it down like this: 100234 +678123 --------- 7 Now look at the tens place, where the first number has 3 tens and the second number has 2 tens. That makes 5 tens, so we continue: 100234 +678123 --------- 57 You just keep on like this until you get to the left end, like this: 100234 +678123 --------- 778357 For your problem, that is absolutely all you need to do. However, I should warn you that it can get more complicated than this. What if the 2 numbers were 100,294 and 678,153 ? Then you still start the same way, and after you do, the ones place it looks like this: 100294 +678153 --------- 7 So now we look at the tens place where we have 9 tens in the first number and 5 tens in the second number. Add that together and you get 9+5 tens, or 14 tens. We cannot write 14 in a place with room just for one digit. What to do? No big problem, really. 14 tens is just 10 tens plus 4 tens, right? That's the same as 1 hundred plus 4 tens. What we'll do is just write down the 4 tens for right now, and make SURE to remember to add on an extra hundred when we get to that step. Okay, let's do that: 100294 +678153 --------- 47 We wrote down 4 in the tens place of the answer, but we had better remember to make up for that in the "hundreds" step coming up: 100294 +678153 --------- 447 Normally, we would add 2+1 to get 3 in the hundreds place, but we instead needed to add on an extra one from the previous step when we were doing the tens. When you start getting this in school, you will probably hear the word "carry" or "carrying" used. What we just did would be called "carrying a 1 to the hundreds place". If you really understand what is happening, like we do in this problem, then it is fine to talk like it that way. Anyway, from here on the problem is exactly the same as before: 100294 +678153 --------- 778447 This answer may be a bit longer than you expected, but look on it as an advance warning of what is coming up soon. Have fun. I hope this helps. -Doctor Mike, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
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