1. **Stating the problem:** Write the given numbers in words. 2. **Number a:** $6 \times 100000 + 9 \times 1000 + 3 \times 100 + 2 \times 10 + 8 \times 1$ Calculate the value: $$6 \times 100000 = 600000$$ $$9 \times 1000 = 9000$$ $$3 \times 100 = 300$$ $$2 \times 10 = 20$$ $$8 \times 1 = 8$$ Sum all: $$600000 + 9000 + 300 + 20 + 8 = 609328$$ Write in words: **six hundred nine thousand three hundred twenty-eight**. 3. **Number b:** $7 \times 1000000 + 2 \times 100000 + 8 \times 1000 + 3 \times 100 + 2 \times 10 + 8 \times 1$ Calculate the value: $$7 \times 1000000 = 7000000$$ $$2 \times 100000 = 200000$$ $$8 \times 1000 = 8000$$ $$3 \times 100 = 300$$ $$2 \times 10 = 20$$ $$8 \times 1 = 8$$ Sum all: $$7000000 + 200000 + 8000 + 300 + 20 + 8 = 7208328$$ Write in words: **seven million two hundred eight thousand three hundred twenty-eight**. 4. **Number c:** $5 \times 100000 + 6 \times 1000 + 7 \times 10 + 9 \times 1$ Calculate the value: $$5 \times 100000 = 500000$$ $$6 \times 1000 = 6000$$ $$7 \times 10 = 70$$ $$9 \times 1 = 9$$ Sum all: $$500000 + 6000 + 70 + 9 = 506079$$ Write in words: **five hundred six thousand seventy-nine**. 5. **Number d:** $3000000 + 80000 + 4000 + 900 + 70$ Sum all: $$3000000 + 80000 + 4000 + 900 + 70 = 3087970$$ Write in words: **three million eighty-seven thousand nine hundred seventy**. 6. **Number e:** $400000 + 2000 + 800 + 70 + 6$ Sum all: $$400000 + 2000 + 800 + 70 + 6 = 402876$$ Write in words: **four hundred two thousand eight hundred seventy-six**. 7. **Number f:** $20000000 + 300000 + 60000 + 700 + 5$ Sum all: $$20000000 + 300000 + 60000 + 700 + 5 = 20360705$$ Write in words: **twenty million three hundred sixty thousand seven hundred five**. 8. **Number a (words to number):** $2 397 604$ Write in words: **two million three hundred ninety-seven thousand six hundred four**. 9. **Number b (words to number):** $51 200 143$ Write in words: **fifty-one million two hundred thousand one hundred forty-three**.