| 23 | Adding 1 to 100A famous trick | Easy | Lemma | PairingArithmetic series | |
| 592 | Digits of 2¹⁰Digits | Easy | Lemma | Digits | |
| 594 | Casting out ninesDigits | Easy | Lemma | Digits | |
| 595 | Units digit of 7⁷Digits | Easy | Lemma | Digits | |
| 596 | Last two digitsDigits | Easy | Lemma | Digits | |
| 597 | The eleven testDigits | Easy | Lemma | Digits | |
| 1096 | Base‑7 representationDigits | Easy | Hall & Knight | base conversionpositional notation | |
| 1097 | Base‑5 representationDigits | Easy | Hall & Knight | base conversionpositional notation | |
| 1098 | Binary representationDigits | Easy | Hall & Knight | base conversionbinary | |
| 1099 | Base‑3 representationDigits | Easy | Hall & Knight | base conversionpositional notation | |
| 1100 | Base‑9 representationDigits | Easy | Hall & Knight | base conversionpositional notation | |
| 1101 | Base‑4 to base‑5 conversionDigits | Easy | Hall & Knight | base conversionpositional notation | |
| 1108 | Convert from duodecimalDigits | Easy | Hall & Knight | base conversiondigits | |
| 1109 | Decimal to duodecimalDigits | Easy | Hall & Knight | base conversionfractional part | |
| 1110 | Ternary to nonaryDigits | Easy | Hall & Knight | base conversiongrouping digits | |
| 1111 | Septenary to vulgar fractionDigits | Easy | Hall & Knight | base conversionfraction reduction | |
| 1112 | Base for 182 as 222Digits | Easy | Hall & Knight | base conversionpositional notation | |
| 1510 | Value of 0.4 in base 7Digits | Easy | Hall & Knight | base conversionfractions | |
| 1511 | Value of 0.42 in base 7Digits | Easy | Hall & Knight | base conversionfractions | |