The new numbers after subtracting remainders are:
280 - 4 = 276
1245 - 3 = 1242
Prime factors of 276 = 23 × 3 × 2
Prime factors of 1242 = 2 × 3 × 3 × 3 × 23
Therefore HCF of 276 and 1242 is:
2 × 3 × 23 = 138
Hence the greatest number which divides 280 and 1245 leaving remainder 4 and 3 respectively is 138
