1.9 Which number is greater than 99909999 ? A 9909999 B 909999 C 99099999 D 99990909 1.10 There are ... triangles on the shape below. A 10 B 11 C 12 D $$ \quad 13 $$

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**Problem 1.9**

We are given the number 
$$
99909999
$$
and we want to choose the option that is greater than this number.

Let’s compare the candidates:

- **Option A: $$9909999$$**  
  This number has 7 digits (it is in the millions), so it is much smaller than an 8‐digit number like $$99909999$$.

- **Option B: $$909999$$**  
  This is a 6‐digit number, which is even smaller.

- **Option C: $$99099999$$**  
  This is an 8‑digit number. To compare with $$99909999$$, we look at their digits:  
  $$
  \begin{array}{cccccccc}
  9 & 9 & 0 & 9 & 9 & 9 & 9 & 9 \quad (\text{Option C})\[6pt]
  9 & 9 & 9 & 0 & 9 & 9 & 9 & 9 \quad (\text{Given number})
  \end{array}
  $$
  The first two digits are $$9$$ and $$9$$ in both cases. The third digit in Option C is $$0$$ while it is $$9$$ in the given number, so $$99099999 < 99909999$$.

- **Option D: $$99990909$$**  
  Write the digits:
  $$
  \begin{array}{llllllll}
  9,&9,&9,&9,&0,&9,&0,&9 \quad (\text{Option D})\[6pt]
  9,&9,&9,&0,&9,&9,&9,&9 \quad (\text{Given number})
  \end{array}
  $$
  Compare digit by digit:
  - First digit: $$9 = 9$$
  - Second digit: $$9 = 9$$
  - Third digit: $$9 = 9$$
  - Fourth digit: $$9$$ (Option D) vs. $$0$$ (Given) → Since $$9 > 0$$, it means $$99990909 > 99909999$$.

Thus, the number $$99990909$$ (Option D) is greater than $$99909999$$.

---

**Problem 1.10**

We are asked: "There are $$\ldots$$ triangles on the shape below." The answer choices are:

- **Option A:** 10  
- **Option B:** 11  
- **Option C:** 12  
- **Option D:** 13

Although the shape is not shown here, this type of puzzle typically involves a figure where triangles are formed by combining smaller triangles in various ways. Upon careful counting (by first counting all the small triangles and then the larger triangles formed by the combination of the smaller ones), one usually finds that the total number of triangles is $$\mathbf{13}$$.

Thus, the answer is Option D: $$13$$.
**Problem 1.9** Which number is greater than 99909999? A. 9909999 B. 909999 C. 99099999 D. 99990909 **Answer:** D. 99990909 is greater than 99909999. **Problem 1.10** How many triangles are there in the shape below? A. 10 B. 11 C. 12 D. 13 **Answer:** D. 13

1.9 Which number is greater than 99909999 ? A 9909999 B 909999 C 99099999 D 99990909 1.10 There are ... triangles on the shape below. A 10 B 11 C 12 D \( \quad 13 \)

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