homework challenge

[naominudge]

I am stumped by this question given to me by my maths teacher.

Using the numerals 1,7,7,7 and 7 calculate the number 100. You can use +,-,x or divide and also use brackets if needed., eg, (7-1)=6 x7=42+(7X7)49=91+7=98.
The nearest I have got is 99 or 102. My teacher said it took her a while but once she looked at the answer it was obvious! Even my mum is perplexed!

 

[Deleted member 4993]

I am stumped by this question given to me by my maths teacher.

Using the numerals 1,7,7,7 and 7 calculate the number 100. You can use +,-,x or divide and also use brackets if needed., eg, (7-1)=6 x7=42+(7X7)49=91+7=98.
The nearest I have got is 99 or 102. My teacher said it took her a while but once she looked at the answer it was obvious! Even my mum is perplexed!

177 - 77 = ??

 

[stapel]

Using the numerals 1,7,7,7 and 7 calculate the number 100. You can use +,-,x or divide and also use brackets if needed., eg, (7-1)=6 x7=42+(7X7)49=91+7=98.

The solution posted here assumes that you can use concatenation (that is, lining the digits next to each other to form larger values, such as using 1 and 7 to form 17).

Is this allowed? It isn't always, though it surely would be nice if it is! :wink:

Eliz.