Question

[Nguyễn Bá Huy]

tính:A=1+2+3+4+...+100

A có chia hết cho 10 không?

Answer 1

[Namikaze Minato]

SSH: ( 100 - 1 ) : 1 + 1 = 100

Tổng: ( 1 + 100 ) . 100 : 2 = 5050 \(⋮\)10 

\(\text{\Rightarrow A=1+2+3+4+...+100⋮10}\)

Answer 2

[❥一Ǥoɗɗεşş øf iηէεℓℓεcէ︵♛╾━╤デ╦︻]

A\(=1+2+3+4+...+100\)

 \(=\frac{\left(100+1\right)\times100}{2}\)

 \(=\frac{101\times100}{2}\)

 \(=50\times101\)

 \(=5050⋮10\)