Well, darling, to write 18 in index form, you simply express it as 2^1 x 3^2. That's the fancy math way of saying 2 to the power of 1 times 3 squared. So, there you have it, 18 all dressed up in its index form finery.
"index" is the singular form - "indices" is the plural :)
18 * * * * * No! 2*3*5 = 30
The possessive form of the singular noun index is index's.
indices or indexes
The plural form for the noun index is indexes.
40.000000 in standard index form is 4.0 × 101
Index form of 9765625 is 9.765625 × 106
5,200 in standard index form = 5.2 × 103
8890 in standard index form = 8.89 × 103
The singular is the noun "index".
Index books is the plural form.