A heap of stones can be made up into groups of 21. When made up into groups of 16, 20, 25 and 45 there are 3 stones left in each case. How many stones at least can there be in the heap?
Correct answer: A. 7203
- A. 7203
- B. 2403
- C. 3603
- D. 4803
Explanation
The heap leaves remainder 3 for division by 16, 20, 25 and 45, so n - 3 must be a multiple of their least common multiple, 3600. Also n must be divisible by 21; testing n = 3600k + 3 gives k = 2 as the least positive solution, so n = 7203 stones. The likely mistake is option b, which has the remainder 3 pattern but is not divisible by 21.
Last updated
About Sequences and Series
Sequences describe ordered terms formed by a pattern, while series represent the sum of those terms. Questions cover arithmetic and geometric sequences, their nth terms, common difference or ratio, finite sums, and applications, with the sequence itself kept distinct from the corresponding series.
Practise Algebra
269 free Algebra MCQs from Mathematics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Mathematics questions like this
Mathematics is on 67 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.