Space Distances

Well done to everybody who calculated these space distances. Lots of children sent in the answers, but only a few children explained their working. 

The children from Wallbrook Primary in the UK said:

To answer the questions 1-5, you needed to find the starting figure which was 150,000,000km. We then had to add individual powers of ten for each question e.g. 150,000,000km + 1,000km = 150,001,000km.

To answer questions 6-10, we started with 375,000,000km and then subtracted each individual power of ten e.g. 375,000,000km - 100,000km = 374,900,000km. Another example is 375,000,000km - 100km = 374,999,900km. An easy mistake to make would be to think 9s would appear in every column. To check we were correct, we had to add our power of ten to our answer to make sure it added up to our starting number.

Esther and Zaki from the Bristol Hospital Education Service in the UK noticed some patterns in their answers. Zaki said:

When I started the addition problems, I noticed that the number I was adding got 10x bigger each time. In the sum, the '1' moved up the place value columns by one column each time. After the first couple of calculations, I was able to use the pattern to predict the calculations.

Although I added each distance separately, I could also easily calculate how much the total would be if I combined all of the extra distances in one sum.

I predicted there would be a similar pattern in the subtraction because the number being subtracted also got 10x bigger each time. I found that in the answer, the '9's disappeared from the place value columns one by one as the amount being subtracted got larger.

Esther sent in this picture and talked about the patterns in the numbers:

Thank you all for sharing your ideas with us!