Question

Quantos multiplos de 3
existem entre 300 e 920 e qual seria a soma desses termos

Answer 1

920:3=306,666...
306.3=918

a1=300
an=918
r=3
an=a1+(n-1).r
918=300+(n-1).3
918=300+3n-3
918=297+3n
3n=918-297
3n=621
n=621/3
n=207

S207=(300+918).207/2
S207=1218.207/2
S207=252126/2
S207=126063