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Missing digit in Maths calculation

Hello. Could anyone help me with the following questions. If you could explain one of them I will probably be able to do the rest. This is probably very easy to most of you but I wasn't there for the lesson and the format is quite weird for me. Thanks a million

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Reply 1

Notnek

Original post by etel

Have you made any progress? Please post all your working.

If you haven't made any progress then start with a) : what number must go in the square below the 7 and the 9? If you're unsure, imagine all the numbers were there and you were doing the long multiplication.

Reply 2

etel

Original post by Notnek

This is what I got so far...

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Reply 3

Notnek

Original post by etel

This is what I got so far...

6 x 9 will give you the 2 digit number circled after adding on what was carried over in the last step. Do you agree?

This 2 digit number must end in an 8 so...

Please post your thoughts if you're still stuck.

(edited 6 years ago)

Reply 4

etel

Original post by Notnek

I think I may have completed it.

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Reply 5

Notnek

Original post by etel

I think I may have completed it.

That's correct!

Have a go at the others and try not to give up too quickly. These take a lot of thought and logic but it will feel good if you can complete them yourself without help :smile:

Of course let us know if you're completely stuck and we can help.

Reply 6

etel

Could you guide me on where to start on B as C seems to be quite similar to A?

Reply 7

Notnek

Original post by etel

Could you guide me on where to start on B as C seems to be quite similar to A?

Please have a really good think about it and post all your thoughts if you're completely stuck. I may not be able to help tonight but others may be free.

Actually I should ask : are you comfortable with long division?

Reply 8

etel

Original post by Notnek

I can do long division however struggle working backwords. Thank you for all of your help anyway.

Reply 9

Notnek

Original post by etel

I can do long division however struggle working backwords. Thank you for all of your help anyway.

Try for another 10 mins and let me know if you still need help. I may be able to give it a go tonight if no one else is helping.

Reply 10

etel

Original post by Notnek

Try for another 10 mins and let me know if you still need help. I may be able to give it a go tonight if no one else is helping.

Thanks I have done C I am doing B now.

Reply 11

ghostwalker

Original post by etel

Thanks I have done C I am doing B now.

Only got time for one post.

For B, if we can work out what the 2-digit divisor is to start, we can then work back from the end of the calculation.

So, refering to the red lines. 3 x some digit produes a number ending in 4. Hence the digit must be....

Then refering to the green lines. 3 x our two digit divisor, produces a number which when subtracted from a number between 60 and 69 produces a number between 10 and 19

So, our 2-digit divisor must be...

Then work back from the end.