Delhi Police Constable Exam Model Paper 5

GIVEN: Numbers from 0 to 1000.
CALCULATION: Since from 0 to 1000 only two – digits and three digits numbers appeared.
Digits ‘1’ and ‘2’ can appear either at first two places or at last two places.
Between 0 – 100: only 12 is the number in which digits ‘1’ and ‘2’ appears together.
Between $101\mathit{–}200:112,120,121,122,123,124,125,126,127,128$ and 129 = 11
Between $201\mathit{–}1000:212,312,412,512,612,712,812$ and 912 = 8
Required number = 1 + 11 + 8 = 20