Question

find the sum 73+74+75+76+77+78+79+80+81+82+83+84+85+86+87 using short cut method​

Answer 1

Answer:

$((88 \times 87) \div 2) -( (73 \times 72) \div 2) \\ = 3828 - 2628 \\ = 1200$

Step-by-step explanation:

sum of first 87 natural numbers - sum of first 72 natural numbers

Answer 2

Answer:

Step-by-step explanation:

to find the sum:

let S= 73+74+75+76+77+78+79+80+81+82+83+84+85+86+87

 + S = 87+86+85+84+83+82+81+80+79+78+77+76+75+74+73

=2S=160+160+160+160+160+160+160+160+160+160+160+160+160+160+160

=2S= 15 x 160

= S = 15 x 80

=S = 1200