Answer :

To find the smallest number which, when increased by 17, is exactly divisible by both 520 and 468, we need to follow these steps:

### Step 1: Calculate the Least Common Multiple (LCM)

First, we need to calculate the Least Common Multiple (LCM) of 520 and 468.

1. Prime Factorization:
- [tex]\( 520 = 2^3 \times 5 \times 13 \)[/tex]
- [tex]\( 468 = 2^2 \times 3 \times 3 \times 13 \)[/tex] or [tex]\( 468 = 2^2 \times 3^2 \times 13 \)[/tex]

2. LCM Calculation:
- LCM is found by taking the highest power of each prime factor appearing in the factorizations of both numbers.
- Highest power of 2: [tex]\( 2^3 \)[/tex] (from 520)
- Highest power of 3: [tex]\( 3^2 \)[/tex] (from 468)
- Highest power of 5: [tex]\( 5^1 \)[/tex] (from 520)
- Highest power of 13: [tex]\( 13^1 \)[/tex] (common in both)

Combining these, the LCM of 520 and 468 is:

[tex]\[ \text{LCM} = 2^3 \times 3^2 \times 5 \times 13 \][/tex]

Calculating this:

[tex]\[ 2^3 = 8 \][/tex]
[tex]\[ 3^2 = 9 \][/tex]
[tex]\[ \text{Multiplying these together: } 8 \times 9 = 72 \][/tex]
[tex]\[ 72 \times 5 = 360 \][/tex]
[tex]\[ 360 \times 13 = 4680 \][/tex]

So, the LCM of 520 and 468 is 4680.

### Step 2: Find the Smallest Number

We already know that when the smallest number is increased by 17, it should be divisible by both 520 and 468. This means the smallest number + 17 must be a multiple of their LCM, 4680.

### Step 3: Derive the Smallest Number

To find the smallest number:
[tex]\[ \text{Smallest number} = \text{LCM} - 17 \][/tex]
[tex]\[ \text{Smallest number} = 4680 - 17 \][/tex]
[tex]\[ \text{Smallest number} = 4663 \][/tex]

Thus, the smallest number which, when increased by 17, is exactly divisible by both 520 and 468, is 4663.

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