Question

Noam solved the equation for k using the following calculations.

k - 7.6 = 10.35
+ 7.6 + 7.6
----------------
k=17.41

What error, if any, did he make?

1. He should have subtracted 7.6 instead of adding it.
2. He should have subtracted 10.35 from both sides.
3. He made a computation error when he added 10.35 + 7.6
4. He made a computation error when he added -7.6 and 7.6

Answer 1

He made a computation error when he added 10.35+7.6

Explanation:

Answer 2

3) He made a computation error when he added 10.35+7.6

Explanation:

Steps to add decimals:

1)Write down the numbers, one under the other, with the decimal points lined up

2) Put in zeros so the numbers have the same length

3) Then add using column addition, remembering to put the decimal point in the answer

Applying the above steps:

line the decimals up 10.35

7.6

Putting zero to get same length

10.35

7.60

Addition:

10.35

+7.60

......................

17.95

Now we can see that, there is error when he added 10.35 + 7.6