What is the value of
(37+38+39+···+86) ?

The number 63_42_0 is a 7-digit number divisible by both 3 and 5. If the thousands digit is greater than the tens digit, then which of the following options gives the correct digits in the thousands place and the tens place respectively?

What is the sum of the first 60 natural numbers?

Three positive integers are such that the difference between the largest and the smallest number is 180.
The HCF of the three numbers is the greatest possible, and the smallest number is 90.
If the middle number differs from the smallest number by 60, what is the HCF of the three numbers?

Three positive integers are in the ratio 3 : 5 : 7. The difference between the largest and the middle number is 56. The LCM of the smallest and the largest number is 588. What is the sum of the three numbers?