How to Calculate IRR on the BA II Plus
IRR is the per-period discount rate that makes the cash-flow stream worth exactly zero. Same CF data as NPV — one different key at the end.
Step by step
- 1
Enter the cash flows exactly as for NPV
[CF], [2ND] [CLR WORK], CF0 negative, then the inflows with frequencies.
[CF][2ND][CLR WORK]1000[+/-][ENTER]
- 2
Press IRR and compute
No rate to enter — the calculator solves for it.
[IRR][CPT]
- 3
Read the result as a percentage
T5 flows (−1000, 600, 600) give IRR = 13.07%. Compare it with your required rate to decide.
- 4
If Error 5 appears
The flows never change sign (e.g. 100, 100, 100) or no root exists. Clear with [CE/C] and re-check CF0’s sign — the classic slip.
Worked example (T5 + T15): 13.07% and an Error 5
−1000, 600, 600 → IRR = 13.07% (13.066239 at DEC = 6). Replace the flows with 100, 100, 100 and the machine shows Error 5 — all-positive flows have no IRR.
[CF][2ND][CLR WORK]1000[+/-][ENTER][↓]600[ENTER][↓][↓]600[ENTER][IRR][CPT]
Web practice cannot replace the physical calculator in a proctored exam — only calculators on the exam organizer’s current list are allowed.
Frequently asked questions
Why does Error 5 show for all-positive flows?
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Discounting positive numbers always stays positive — no rate brings the sum to zero, so there is nothing to solve. See the Error 5 guide for the full checklist.
Can IRR have multiple answers?
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Yes, when the flows change sign more than once. Keysheet returns the root nearest a 10% start — treat multi-sign problems with care and cross-check with NPV.
Should I decide with IRR or NPV?
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IRR is intuitive for comparing rates; NPV is authoritative for value, especially when projects differ in scale. When they disagree, NPV wins.