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After every factorial from 5! onward, the ones digit contains a 0. If you multiply at least 2 numbers with a ones digit of 0, the tens digit will eventually also be a 0. Therefore, the tens digit in the sum 1!+2!+3!...+20!, the tens digit will be 0.
I think the answer is 1. One is the tens digit number. I know that because all factorials over 10 has been multiplied by 2, 5, and then 10, all future tens digit values are 0. So only 1! to 9! matter. So i just calculated that, making note of just the 10s digit number, for all number after 5, because anything that is a multiple of 5 and 2 has a unit digit of 0. Basically, i got the answer of: the value of the tens digit is 1.
I think the answer is 0, i did it hard copy.
ReplyDeleteAfter every factorial from 5! onward, the ones digit contains a 0. If you multiply at least 2 numbers with a ones digit of 0, the tens digit will eventually also be a 0. Therefore, the tens digit in the sum 1!+2!+3!...+20!, the tens digit will be 0.
ReplyDeleteI think the answer is 1. One is the tens digit number. I know that because all factorials over 10 has been multiplied by 2, 5, and then 10, all future tens digit values are 0. So only 1! to 9! matter.
ReplyDeleteSo i just calculated that, making note of just the 10s digit number, for all number after 5, because anything that is a multiple of 5 and 2 has a unit digit of 0.
Basically, i got the answer of: the value of the tens digit is 1.
I got 0, I did it hardcopy
ReplyDelete