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Zorluk: OrtaGreatest Common Divisor (GCD) and Least Common Multiple (LCM)

An inventory manager is organizing items into storage boxes. When the items are packed into boxes of 2424, 3636, or 4545 items each, there are always 1111 items remaining unpacked. If the total number of items is between 700700 and 1,0001,000, how many items are there in total?

Cevap: 731

Cevap

731
The number of items NN satisfies N11(mod24)N \equiv 11 \pmod{24}, N11(mod36)N \equiv 11 \pmod{36}, and N11(mod45)N \equiv 11 \pmod{45}. Consequently, N11N - 11 is a multiple of LCM(24,36,45)\text{LCM}(24, 36, 45). The prime factorizations are 24=23×324 = 2^3 \times 3, 36=22×3236 = 2^2 \times 3^2, and 45=32×545 = 3^2 \times 5. The LCM is 23×32×5=3602^3 \times 3^2 \times 5 = 360. Thus, N=360k+11N = 360k + 11 for some positive integer kk. Testing values of kk within the range 700<N<1,000700 < N < 1,000 yields k=2k = 2, giving N=360(2)+11=731N = 360(2) + 11 = 731.

Adım Adım Çözüm

1
Find the Least Common Multiple (LCM) of the divisors 24, 36, and 45.
LCM(24, 36, 45) = 360
Any number that leaves a constant remainder when divided by a set of numbers must be a constant remainder greater than a common multiple of those numbers.
2
Formulate the general equation for the total number of items N.
N = 360k + 11
Adding the common remainder 11 to any multiple of the LCM yields a valid total number of items.
3
Evaluate integer values of k to satisfy the constraint 700 < N < 1,000.
k = 2 gives N = 731
k = 1 gives 371, which is too small, and k = 3 gives 1,091, which exceeds 1,000.

Anahtar Kavram

Least Common Multiple (LCM) with Constant Remainder
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