1) (25^3/49) (14^2/10^6)
= (15625/49) (196/1000000)
= (15625 196) / (49 1000000)
= 3055625 / 49000000
= 0.062421(3 decimal places)

2) (7^40 + 7^38 - 2 7^39) / (6^2 49^19)
= (5764801 + 5764801 - 2 40353607) / (36 21767490951634)
= (11529602 - 80707214) / 78242847345924
= -69177612 / 78242847345924
≈ -0.88358 * 10^-9

3) (36^3 / 18^4) (15^2 / 10^3)
= (46656 / 104976) (225 / 1000)
= (46656 225) / (104976 1000)
= 104973600 / 104976000
= 0.999971(3 decimal places)

4) (3^48 - 3^47 + 17 3^46) / (27^15 23)
= (7262837703 - 2420945901 + 17 807315389) / (22409486899694803355541 23)
= (4841891802 + 13724301569) / 515030119670907463167
= 18566293371 / 515030119670907463167
≈ 3.61039 * 10^-11