The  HCF of three numbers 98, 175 and 210 will be :

6 3  5 7

7

98 = 2 x 7 x 7 175 = 5 x 5 x 7 210 = 2 x 3 x 5 x 7 So, HCF of three numbers 98, 175 and 210 = 7