We know that 7 = 7, C = 12 and A = 10.
Therefore (7CA)16 = (7 × 162) + (12 × 161) + (10 × 160)
(7CA)16 = (7 × 256) + (12 × 16) + (10 × 1)
(7CA)16 = 1792+192+10
(7CA)16 = (1994)10
Hence, 7CA (hex) to decimal is 1994.