Hello, MrDiedel!

What is the source of this mathematical rubbish?

Are you omitting some clarification?

In the material I'm studying, it says the following;

. . 1. A number sequence is when addition is written horizontally.

. . 2. A number sentence is when subtraction and multiplication are written horizontally.

Is this really specific to addition, subtraction and multiplication, or can they all be interchanged?

Could I say that, 2 + 4 = 6 is a number sentence and that 4 x 5 = 20 is a number sequence?

Statement 1 makes no sense.

A number sequence is an ordered list of numbers.

Example: 2, 5, 8, 11, 14, ...

. . which may or may not have a pattern.

We see that: . isa number sequence . . . and neither is:not

Who caresif it is written horizontally or vertically?

Statement 2make sense if we knew what a "number sentence" is.might

Perhaps it is an English sentence containing a number?

Example: "There are twelve objects in a dozen."

I seriously recommend you discard that material immediately.

It is chillingly irrational and dangerously wrong.