Question

Quantos Multiplos de 11 existem entre 100 e 1000 ?

Answer 1

110, 121, 132, 143, 154, 165, 176, 187, 198, 209, 220, 231, 242, 253, 264, 275, 286, 297, 308, 319, 330, 341, 352, 363, 374, 385, 396, 407, 418, 429, 440, 451, 462, 473, 484, 495, 506, 517, 528, 539, 550, 561, 572, 583, 594, 605, 616, 627, 638, 649, 660, 671, 682, 693, 704, 715, 726, 737, 748, 759, 770, 781, 792, 803, 814, 825, 836, 847, 858, 869, 880, 891, 902, 913, 924, 935, 946, 957, 968, 979, 990 

Answer 2

a1 = 110
an = 990
n = ?
r = 11

an = a1 + (n-1).r
990=110 + (n-1).11
990-110 =11n- 11
880 + 11 = 11n
891 = 11n
n=891/11
n = 81 numeros