Question 1150957
The smallest three-digit number divisible by 5 is 100 and the largest is 995
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Therefore, this is an arithmetic sequence - the formula for the sum of an arithmetic sequence is
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Sum of first n terms = (n/2) * (a + L), where a is the first term and L is the last term
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the formula for the nth term is
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a(n) = a +d * (n-1), where a is the first term and n is the common difference
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995 = 100 +5 * (n-1)
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995 = 100 + 5n -5
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5n = 900
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n = 180
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sum of first n terms = (180/2) * (100 + 995) = 90 * 1095 = 98550
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the sum of all positive three-digit numbers divisible by 5 = 98,550
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