1) 38²-17² = (38-17)(38+17) = 21*55 = 55 = 55
47²-19² (47-19)(47+19) 28*66 28*3 84
2) 53²-27² = (53-27)(53+27) = 26*80 = 1*20 = 20 =4
79²-51² (79-51)(79+51) 28*130 7*5 35 7
3) 181²-61² = (181-61)(181+61) = 120 * 242 = 12 * 121 = 1* 121 = 121
319²-209² (319-209)(319+209) 210 * 528 21 * 264 21* 22 462
4) 200²-60² = (200-60)(200+60) = 140 * 260 = 14 = 7
420²-160² (420-160)(420+160) 260 * 580 58 29
5) 300²-100² = (300-100)(300+100) = 200 * 400 = 40 = 5
140²-60² (140-60)(140+60) 80 * 200 8
6) 55²-145² = (55-145)(55+145) = -90 * 200 = -2 * 200 = -2*40 = -80
203²-22² (203-22)(203+22) 181 * 225 181 * 5 181 181