Modulus 10^9 +7


In few questions we need to compute the answer in modulo 10^9+7 . How to do that? Do we just need to find modulo of ans with 10^9+7 i.e. ans%1000000007 ?

Hritesh Mourya

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1 Answer

preda2or 00:57, Oct 12
Shubham Kumar Gupta

you are correct that we have to find  ans% (10^9 +7), but in such questions the val of ans becomes so large(it won't fit in long long) that if you just calculate the actual ans and then modulo it in the final step you will get a wrong result. Hence, in such questions you have to apply modular properties.

Some of the properties which are generally used are :

1. (a + b) % c  = ((a % c) + (b % c)) % c
2. (a * b) % c  =  ((a % c) * (b % c)) % c
3. (a - b) % c  =  ((a % c) - (b % c) + c) % c

Follow this link for more details : modulo 10^9 + 7 

Please make sure the answer is not too short
hritesh0027 (Hritesh Mourya) 18:12, Oct 13

Thanks a lot..