Any question ?

1 = 1 + 2 = 1 + 2 + 3 = 1 + 2 + 3 + 4 = 1 + 2 + 3 + 4 + 5 = 1 + 2 + 3 + 4 + ... + n = 1361015?

1 + 3 + 5 + 7 + ... = n2

n1234...n1357...2n-1

1.21 + 2.22 + 3.23 + 4.24 + ... + 50.250 = ... Berapa digit terakhir dari hasil penjumlahan di atas?

humanHealthChanceWell-educationEnough foodWonderful pairCheersEtc.Etc.GOD1221o