(i) 130

Applying subtraction method, We have,

130 – 1 = 129

129 – 7 = 122

122 – 19 = 103

103 – 37 = 66

66 – 61 = 5

∵ Next number to be subtracted is 91, which is greter than 5

Hence, 130 is not a perfect cube.

(ii) 345

Applying subtraction method, We have,

345 – 1 = 344

344 – 7 = 337

337 – 19 = 318

318 – 37 = 281

281 – 61 = 220

220 – 91 = 129

129 – 127 = 2

∵ Next number to be subtracted is 169, which is greter than 2

Hence, 345 is not a perfect cube

(iii) 792

Applying subtraction method, We have,

792 – 1 = 791

791 – 7 = 784

784 – 19 = 765

765 – 37 = 728

728 – 61 = 667

667 – 91 = 576

576 – 127 = 449

449 – 169 = 280

280 – 217 = 63

∵ Next number to be subtracted is 271, which is greter than 63

Hence, 792 is not a perfect cube

(iv) 1331

Applying subtraction method, We have,

1331 – 1 = 1330

1330 – 7 = 1323

1323 – 19 = 1304

1304 – 37 = 1267

1267 – 61 = 1206

1206 – 91 = 1115

1115 – 127 = 988

988 – 169 = 819

819 – 217 = 602

602 – 271 = 331

331 – 331 = 0

∵ Subtraction is performed 11 times.

Hence, 1331 is a perfect cube