# Stuck in I.11.4

**URL:** <https://discuss.pennylane.ai/t/stuck-in-i-11-4/3972>\
**Category:** Codebook\
**Created:** [January 27, 2024, 7:41am UTC](https://discuss.pennylane.ai/t/stuck-in-i-11-4/3972 "2024-01-27T07:41:55Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![SUDHIR\_KUMAR\_SAHOO](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/sudhir_kumar_sahoo/32/2254_2.png) [@SUDHIR\_KUMAR\_SAHOO](https://discuss.pennylane.ai/u/SUDHIR_KUMAR_SAHOO)\
**Post date:** [January 27, 2024, 7:41am UTC](https://discuss.pennylane.ai/t/stuck-in-i-11-4/3972/1 "2024-01-27T07:41:55Z")

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Hello I want a conceptual clarification of as we know %%(Z \otimes I)(I \otimes Z) = Z \otimes Z$ How to get that problem solved please Help.

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**Author:** ![Ivana\_at\_Xanadu](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/ivana_at_xanadu/32/1852_2.png) [@Ivana\_at\_Xanadu](https://discuss.pennylane.ai/u/Ivana_at_Xanadu)\
**Post date:** [January 29, 2024, 10:18am UTC](https://discuss.pennylane.ai/t/stuck-in-i-11-4/3972/2 "2024-01-29T10:18:17Z")

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Hey @SUDHIR_KUMAR_SAHOO , you’re solving the I.11.4 codercise, right?  
If I understand correctly, is this what you’re wondering about?  
(Z\otimes I)(I \otimes Z) = ZI \otimes IZ = Z \otimes Z

Sometimes, if you get stuck on the code, it can be very helpful to look at the right side of the Codebook, where the mathematics of what you’re coding is explained in detail. 🙂 Could you try to look at the right side of I.11 and see if that helps you understand the left side a bit better? For example, exercise I.11.4 (on the right side!) might be helpful here. 🙂

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**Author:** ![SUDHIR\_KUMAR\_SAHOO](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/sudhir_kumar_sahoo/32/2254_2.png) [@SUDHIR\_KUMAR\_SAHOO](https://discuss.pennylane.ai/u/SUDHIR_KUMAR_SAHOO)\
**Post date:** [January 30, 2024, 5:38pm UTC](https://discuss.pennylane.ai/t/stuck-in-i-11-4/3972/3 "2024-01-30T17:38:31Z")

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@Ivana_at_Xanadu Thanks for your reply. I have already solved that problem.

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**Author:** ![isaacdevlugt](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/isaacdevlugt/32/1159_2.png) [@isaacdevlugt](https://discuss.pennylane.ai/u/isaacdevlugt)\
**Post date:** [January 31, 2024, 11:00pm UTC](https://discuss.pennylane.ai/t/stuck-in-i-11-4/3972/4 "2024-01-31T23:00:25Z")

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Hey @SUDHIR_KUMAR_SAHOO, are you still stuck?

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**Author:** ![SUDHIR\_KUMAR\_SAHOO](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/sudhir_kumar_sahoo/32/2254_2.png) [@SUDHIR\_KUMAR\_SAHOO](https://discuss.pennylane.ai/u/SUDHIR_KUMAR_SAHOO)\
**Post date:** [February 1, 2024, 9:23am UTC](https://discuss.pennylane.ai/t/stuck-in-i-11-4/3972/5 "2024-02-01T09:23:20Z")

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No no. Already cleared that one.

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**Author:** ![isaacdevlugt](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/isaacdevlugt/32/1159_2.png) [@isaacdevlugt](https://discuss.pennylane.ai/u/isaacdevlugt)\
**Post date:** [February 2, 2024, 11:28pm UTC](https://discuss.pennylane.ai/t/stuck-in-i-11-4/3972/6 "2024-02-02T23:28:58Z")

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Okay great! If you have any other troubles along the way please write back to us here 🙂