Make a table of the first digit of the first 20 squares

Questions
1

Hi all, beginner programmer here. I am having trouble with this exercise.

Make a table of the first digit of the first 20 square.

Can anyone help? Thank you.

2

Not exactly sure is this what you looking for

Table[First[IntegerDigits[i^2]], {i, 20}]

(* {1, 4, 9, 1, 2, 3, 4, 6, 8, 1, 1, 1, 1, 1, 2, 2, 2, 3, 3, 4}*)
3

Yes Hans, thank you. How about:

Make a list for numbers n up to 20 in which each element is a column of the values of n, n^2 and n^3

4

There are many ways to do this in WL/Mathematica. Essence of your question is “take a list and display that list in a table-like structure”.

TableForm[Table[{n, n^2, n^3}, {n, 20}], 
 TableHeadings -> {None, {"n", "n^2", "n^3"}}]

(*

n	n^2	n^3
1	1	1
2	4	8
3	9	27
4	16	64
5	25	125
6	36	216
7	49	343
8	64	512
9	81	729
10	100	1000
11	121	1331
12	144	1728
13	169	2197
14	196	2744
15	225	3375
16	256	4096
17	289	4913
18	324	5832
19	361	6859
20	400	8000

*)

As a beginner to WL I would suggest that you review any of the beginner tutorials or the WL starter book.

5

Identical but extended with //Dataset or //Framed or //Dataset//Framed

TableForm[Table[{n, n^2, n^3}, {n, 20}], 
  TableHeadings -> {None, {"n", "n^2", "n^3"}}
  , TableAlignments -> {Right, Center}
  , TableSpacing -> {1.5, 2}
  ] // Framed

4772Dataset.gif
4772Dataset.gif125Ă—390 4.54 KB

6

Perhaps nicer: take a look at attached notebook

niceTable.nb (3.48 KB)

7

There’s no need for an iterator in many such situations, especially as in this one where you’re dealing with consecutive integers and individual functions (power-of-two and IntegerDigits) are listable. To obtain the desired first digits, you may simply do this:

      First /@ IntegerDigits[Range[20]^2]
 (*  {1, 4, 9, 1, 2, 3, 4, 6, 8, 1, 1, 1, 1, 1, 2, 2, 2, 3, 3, 4}  *)

If you want a table, you may use, for example:

      {Range[20], First /@ IntegerDigits[Range[20]^2]} // TableForm
8

Table[Column[{n, n^2, n^3}], {n, 20}]

That´s the answer