5b
5 minutes
aidan writes the counting numbers in order. in
row 1, he writes the first number. in row 2 he
writes the next two numbers, and so on as shown.
what is the thirteenth number in row 16?
row l: 1
ron 2: 2 3
row 3: 4 5 6
and so

133

Step-by-step explanation:

There will be 16 numbers in row 16.

Now, first number of each row are

So, the difference between the numbers is in the Arithmetic sequence.

Let,  S₁₆ = 1 + 2 + 4 + 7 + ............ + t₁₆

And S₁₆ =       1 + 2 + 4 + 7 + .......+ t₁₅ + t₁₆

(-) --------------------------------------------------------------

         0 = 1 + ( 1 + 2 + 3 + 4 + ...... up to 15 terms) - t₁₆ {Subtracting the equations}

⇒ t₁₆ = 1 + 0.5 (15)(15 + 1) = 121

Therefore, the first term of the 16th row is 121.

So, the 13th number of the 16th row will be = 121 + 12 = 133 (Answer)

just take the area of the square and then the area of the circle then subtract the circle area from the squares area

step-by-step explanation: