% ollama run gpt-oss:20b
    >>> Calculate 87654321 * 98765432
    Thinking...
    We need to compute product of 87654321 and 98765432. Straight multiplication. Let's compute.

    87654321 * 98765432.

    We can attempt to compute using big integer multiplication. Maybe use decomposition.

    Let a=87654321, b=98765432.

    We can try to compute with Python-like mental? Let's try.

    Use method: b=98765432 = 100000000 - 1234568? Wait 100,000,000 - 1,234,568 = 98,765,432? Let's check: 100,000,000 
    - 1,234,568 = 98,765,432 correct. So product = a*(100,000,000 - 1,234,568) = a*100,000,000 - a*1,234,568.

    Compute a*100,000,000 = 8,765,432,100,000,000? Wait multiply 87,654,321 by 100,000,000 gives 
    8,765,432,100,000,000? Let's check: 87,654,321 * 100,000,000 = 8,765,432,100,000,000? Actually 87,654,321 * 
    100,000,000 = 8,765,432,100,000,000? Multiply by 10^8: shift 8 digits: 87,654,321 -> 8,765,432,100,000,000? Wait 
    87,654,321 times 10^8 = 8,765,432,100,000,000? Let's do digits: 87,654,321 * 100,000,000 = 8,765,432,100,000,000? 
    Write 87,654,321 followed by 8 zeros: 8,765,432,100,000,000. yes.

    Now compute a*1,234,568.

    a = 87,654,321. Multiply by 1,234,568. Use decomposition: 1,234,568 = 1,200,000 + 34,568? Actually 1,234,568 = 
    1,000,000 + 234,568? Let's use 1,234,568 = 1,234,568. We'll do multiply.

    Option: use long multiplication: 87,654,321 * 1,234,568.

    We can also use a*1,234,568 = a*1,000,000 + a*234,568.

    Compute a*1,000,000 = 87,654,321,000,000.

    Now a*234,568. Compute a*234,568 = a*234,000 + a*568.

    Compute a*234,000 = a*234 * 1000. First a*234: a*200 + a*34.

    a*200 = 17,530,864,200.
    a*34 = a*30 + a*4.

    a*30 = 2,629,629,630.
    a*4 = 350,617,284.
    Sum a*34 = 2,629,629,630 + 350,617,284 = 2,980,246,914.

    Add a*200: 17,530,864,200 + 2,980,246,914 = 20,511,111,114. That is a*234.

    Then a*234,000 = 20,511,111,114,000.

    Now a*568 = a*500 + a*60 + a*8.

    a*500 = 43,827,160,500.
    a*60 = a*6*10. a*6 = 525,925,926; times10 => 5,259,259,260.
    a*8 = 701,234,568.

    Sum: 43,827,160,500 + 5,259,259,260 = 49,086,419,760. + 701,234,568 = 49,787,654,328.

    Now a*234,568 = a*234,000 + a*568 = 20,511,111,114,000 + 49,787,654,328 = 20,560,898,768,328.

    Now a*1,234,568 = a*1,000,000 + a*234,568 = 87,654,321,000,000 + 20,560,898,768,328 = 108,215,219,768,328.

    Now product: a*100,000,000 - a*1,234,568 = 8,765,432,100,000,000 - 108,215,219,768,328 = ?

    Compute:

    8,765,432,100,000,000
    -108,215,219,768,328
    =8,657,216,880,231,672? Let's subtract carefully.

    8,765,432,100,000,000
    - 108,215,219,768,328
    = 8,657,216,880,231,672.

    Check: subtract 108,215,219,768,328 from 8,765,432,100,000,000.

    8,765,432,100,000,000
    - 108,215,219,768,328
    --------------------------------
    = 8,657,216,880,231,672.

    Yes.

    Thus product is 8,657,216,880,231,672.

    Let's double-check via alternative method to ensure no mistakes.

    We can use big-int mental? Let's cross-check using another decomposition: Use b=98,765,432 = 99,000,000 - 234,568? 
    Actually 99,000,000 - 234,568 = 98,765,432. So product = a*99,000,000 - a*234,568.

    Compute a*99,000,000 = a*99 * 1,000,000. a*99 = a*100 - a = 8,765,432,100 - 87,654,321 = 8,677,777,779? Wait 
    compute: a=87,654,321. a*100 = 8,765,432,100. Subtract a gives 8,677,777,779. Yes.

    Then a*99,000,000 = 8,677,777,779 * 1,000,000 = 8,677,777,779,000,000.

    Now subtract a*234,568. We previously computed a*234,568 = 20,560,898,768,328.

    Thus product = 8,677,777,779,000,000 - 20,560,898,768,328 = ?

    Compute: 8,677,777,779,000,000 - 20,560,898,768,328 = 8,657,216,880,231,672. Same result. Good.

    Thus answer is 8,657,216,880,231,672. Provide in numeric form.

    Let's output.
    ...done thinking.

    The product is  

    \[
    87654321 \times 98765432 = 8\,657\,216\,880\,231\,672
    \]