Both numbers has remainder of 5
We can start by subtracting 5 from both numbers
245-5=240
1245-5=1240
We can then proceed to find the Highest Common Factor of 240 and 1240.
One efficient method to find HCF for large numbers is by finding their product of prime factors. The diagram below shows the factor tree method
We then have
240 = 2×2×2×2×3×5 =[tex] 2^{4} [/tex]×3×5
1240 = 2×2×2×5×31 = [tex] 2^{3} [/tex]×5×31
HCF = [tex] 2^{3} [/tex]×5=40
