
Shortcut Trick
Factorize: 64 = 26, 128 = 27, and 4480 = 27 × 5 × 7.
Since 5 and 7 are missing from 64 and 128, A must have 5 × 7 = 35.
The power of 2 in A can be anything from 0 to 7 to maintain the LCM.
Minimum A = 20 × 35 = 35 and Maximum A = 27 × 35 = 4480.
Difference = 4480 − 35 = 4445.
∴ Answer = 4445

Alternate Method
Given:
Numbers: 64, 128, and A. Their LCM is 4480.
Formula used:
LCM = Product of prime factors raised to their highest powers present in the numbers.
Range of possible values for A Min A = 35 (20 × 5 × 7) Max A = 4480 (27 × 5 × 7) A = 35 × 2x (0 ≤ x ≤ 7)
Calculations:
Factorizing the given numbers and LCM:
⇒ 64 = 26
⇒ 128 = 27
⇒ 4480 = 448 × 10 = 128 × 35 = 27 × 51 × 71
⇒ Let A = 2x × 5y × 7z
⇒ Comparing powers in LCM(26, 27, A): Max(6, 7, x) = 7 ⇒ 0 ≤ x ≤ 7
⇒ Max(0, 0, y) = 1 ⇒ y = 1; Max(0, 0, z) = 1 ⇒ z = 1
⇒ Possible values of A = 2x × 35, where x ∈ {0, 1, 2, 3, 4, 5, 6, 7}
⇒ Maximum A = 27 × 35 = 128 × 35 = 4480
⇒ Minimum A = 20 × 35 = 1 × 35 = 35
⇒ Difference = 4480 − 35 = 4445
∴ The correct answer is 4445.

Additional Information
Relationship between HCF and LCM
For any two numbers a and b, a × b = HCF(a, b) × LCM(a, b). Note that this property does not directly apply to three or more numbers.
LCM of Fractions
The LCM of a set of fractions is calculated as: LCM of numerators ÷ HCF of denominators.
HCF of Fractions
The HCF of a set of fractions is calculated as: HCF of numerators ÷ LCM of denominators.
Successive Division Method
HCF can be found by dividing the larger number by the smaller one and repeating the process with the remainder as the new divisor until the remainder is zero.