Question

Calculati sumele :
a) 10+11+12+...+99+100
b) 110+111+112+...+999+900
c) 10+12+14+...+98+100
d) 11+13+15+...+97+99
Va rog frumos , cat mai repede , dau coroana si toate cele , pls 90 pcte dar va rog frumix

Answer 1

a)1+2+....100=100x101:2=5050
1+2+..9=9x10:2=45
10+11+...100=5050-45=5005

b)110+111+....1000=
1+2+3+++1000-(1+2+++110)=
1000x1001:2-110x111:2=
500500-6105=494395

c)10+12+...100=
2+4+6...+100-(2+4+6+8)=
50x102:2-20=2530

d)11+13+...99=
99x100:2=9450
9450:2=4725