We have been asked to find the sum of all two digits natural numbers between 100 and 200 which are divisible by 4.
ML Aggarwal Avichal Publication Arithmetic Progression Chapter 9 question no 20 ii
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Find the sum of all two digits natural numbers between 100 and 200 which are divisible by 4
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(i) The number between 100 and 200 which is divisible by 4= 104, 108, 112, …196 Let the number of terms between 100 and 200 which is divisible by 6= n an = a + (n – 1)d 196= 104 + (n – 1)4
92= (n – 1)4
n – 1 = 23 n = 24
Sum of an AP = Sn = (n/2) [ a + an] Sn = (24/2) × [104 + 196]
= (12) × 300 = 3600