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1.
Number Locks?
On the Number Pad on some keyboards, the numbers can also do other commands, but 6 is Right, not Page Up.
2.
Excelling in Locking values, even while moving.
In Excel, using $ before a grid coordinate means it locks that half of the coordinate, even if it is moved parallel to that coordinate.
3.
Not So Colourful Now, Are Ya?
Carnelian is the only one of these gemstones which can't be black.
4.
Jumping to be Inclusive. Only for 24 hours though.
The Year 2400 will be a leap year, and the others will/were not.
5.
You need to look again.
'A Goal Ink' is not an anagram of 'Look Again'.
6.
Ordering
Oct, Hept, Hex, Pent, But, Prop
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Tri, Squ, Pen, Hex, Hep, Oct
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The others have an order of some sort: 'Tri, Squ, Pen, Hex, Hep, Oct' is the first 3 letters of shapes with 3, 4, 5, 6... sides; '8, 5, 4, 7, 6, 3' is 3 through 8 in alphabetical order; 'Oct, Hept, Hex, Pent, But, Prop' is the prefixes of Alkanes/Alkenes between 3 and 8 in reverse order. The other should be T, F, F, S, S, E: To symbolise 3 through 8.
7.
How lucky are you? Or speed of counting?
7, 14, 21, -41, 20, 21, 21, 13
✓
6, 6, 6, 6, 6, 5, 6, 6, 6, 6, 6, 6, 6
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1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, -1
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All the other number strings have a sum of 77.
8.
Wake up Eight for me, please.
The name of the ∞ symbol is the Lemniscate.
9.
Don't count on what you can see.
Space Space Space Space Space Space
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Space Space Space Space Space Space Space Space Space Space Space Space
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Space Space Space Space Space Space Space Space Space
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There are 6 spaces in the statement.
10.
I square a positive real number, subtract 8 off of it, square root it then re add the 8 to it. I ended with ten. What's the starting number?
https://www.symbolab.com/solver/algebra-calculator/%5Csqrt%7Bx%5E%7B2%7D-8%7D%2B8%3D10
11.
Can you pause this?
11, when written without flicks, is the same as the pause symbol.
12.
You're about to crash. Which of these has an alternate name which is something you could/should do in this situation?
< (I have to put this text here or this symbol doesn't appear)
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A curly bracket { or } can also be known as a brace. You may decide to brace yourself.
13.
Can you cube? Because I obviously can't.
All the other numbers are one more or one less than a cube.
14.
Rotational.
Turn E 90 degrees clockwise
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Turn E 90 degrees anticlockwise
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When rotating E as shown you'll get four symbols: E, M, W and 3. 3 isn't a letter, so is odd.
15.
Copy, Undo, and Cut.
Ctrl and V is paste and isn't listed in the question.